/Engine/Source/Runtime/Slate/Public/Widgets/SVirtualWindow.h
We allow users to control the resolve policy for deferred content. When a virtual window is used in a retainer, we don't want it trying to resolve the deferred content, we instead need it to pass that content up to the non-retained window drawing the retainer. If a virtual window is used in a case like the WidgetComponent, we always want to resolve the deferred content because there won't be another opportunity since the 3D widget has no owner window that can draw it.
void SetShouldResolveDeferred ( bool bResolve )